Excimer laser systems, e.g., single chamber laser systems with pulse stretchers, e.g., applicants' assignee's 7XXX model laser system series and XLA-XXX (MOPA) multi-chamber laser systems utilize pulse stretchers which applicants' assignee refers to as an Optical Pulse Stretchers (“OPuS”). Applicants have found that for certain uses, e.g., for low temperature poly-silicon processing (“LTPS”) high power elongated beam laser annealing or for tightly constricted laser beam characteristics and qualities, such as the very narrow bandwidth, high repetition rate and very restricted pulse variation, e.g., for use in currently employed integrated circuit manufacturing tool employing such laser systems for exposing wafers in such a process, the pulse stretchers can be improved according to aspects of embodiments of the disclosed subject matter.